Kopper nails are all steel raised and are unique in that they are pulled in Utility Poles and in Prescott & Northwestern Railroad ties. The pole nails are found in Ky, Il, OH and Tx.
There is some thoughts that these nails are not Koppers but an unidentified nail manufacturer. However, with the evidence of the K72, I think these very well could be from the Koppers Company. The 1946 probably does not exist. Poles branded with "Koppers" can be found all over East Texas. This set has some minor varieties, mainly in shank lengths and positioning of the letters/numbers. The K72 is actually a "Tack". The picture is much larger than the tack. The head is 1/2 in. and the Shank is 1/4 in. and has a barb on it. This was given to a friend of mine from an employee of the Koppers Company.